The apparatus of the invention deals with stereophonic broadcast transmission equipment. More specifically, a monitor is provided for detecting the stereophonic information contained on a broadcast signal.
Stereophonic transmission on a radio broadcast signal is known in the art. Broadcasts at the high frequency FM spectrum have been conducted for a number of years carrying two channels of information. The two channels of information when detected by an FM receiver properly equipped with demodulation circuitry produces left and right outputs of stereophonic information. Recently, a number of systems have been proposed for transmitting stereophonic information on low frequency signals now carrying monophonic transmissions in the AM broadcast band.
Commercial broadcasters carrying either FM transmission of stereophonic information or the proposed AM stereophonic transmissions require monitoring the transmitted signal to insure a quality consistent with Federal Communications Commission standards and acceptable to the listening audience. Therefore, it is necessary for each broadcaster of stereophonic information to monitor the signal which is being broadcast to insure all broadcast requirements are being met, both legal and publicly acceptable standards.
Therefore, future AM stereophonic broadcasts will require monitor equipment at the broadcast station in order to measure the quality of the AM stereophonic broadcast. Distortion, intermodulation, frequency response, crossover, and other parameters controlled by the Federal Communications Commission and performance levels expected by the public listening audience will need to be verified. The present invention seeks to provide monitor signals from the broadcasted AM stereophonic signal in order for stations to meet its legal and commercial obligations.